Problems wirth Roaming profiles - error 1521

I am having problems getting a roaming profile to work on a Vista RC2 PC.
First I thought it might be me as I have not used Vista or 2003 Server prior
to this test but I see from other posts this is an issue others have had but
has anyone come up with a definitive answer to the cause?

The error is:
event id 1521 for User Profile Service :

"Windows cannot locate the server copy of your roaming profile and is
attempting to log you on with your local profile. Changes to the profile will
not be copied to the server when you log off. This error may be caused by
network problems or insufficient security rights."

I tried this solution - which I assume needs to run only once ever for it to
work for all logged in users?:
The command to disable the autotuninglevel is:

- Click start, All Programs
- Accessories
- Right-click Command Prompt
- Click Run As Administrator
- Type the following: netsh int tcp set global autotuninglevel=disabled
- Press enter
- Restart your computer (not really necessary)

This did not cure the problem.

The server is a Windows 2003 Server Standard and the user is a newly created
test user with just domain user membership.
The profiles SHARE on the server has Administrators and Everyone with Full
Control. At NTFS level I set everyone with Read Only access and then for each
user folder administrators and the user full control with the user as the
owner.

This all works fine on an XP Pro PC.


Help?

Andrew